Silica-based glass, such as soda-lime glass, is prevalent in the manufacture of glass containers and other products. Formation of a raw glass melt typically involves mixing various glass-forming components at elevated temperature. The glass typically has a residence time in a furnace on the order of twenty-four hours to dissolve the solids and refine the glass by driving off gases. The gases must be driven off ultimately to produce a solidified glass product without entrained bubbles. (The process of removing bubbles and bubble-forming gasses in molten glass is called “refining.”) In addition to being undesirably slow, this in-furnace process involves a large amount of space and high-energy input.
The general object of the present disclosure is to provide an apparatus for making silica-based glass, which is compact and modular. Another object of the disclosure is to provide an apparatus for making a silica-based glass melt, which can readily be scaled up or down as needed to provide a desired glass output.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
Apparatus for melting and refining a silica-based glass composition, in accordance with one aspect of the present disclosure, includes a first melting vessel for receiving and melting silica-based glass forming components, a first vertical chamber having an inlet adjacent to a lower and operatively coupled to said first melting vessel to receive melted glass-forming components from said first melting vessel, a second vertical chamber spaced from and separate from the first vertical chamber, and a cross passage connecting an upper end of the first vertical chamber to an upper end of the second vertical chamber. Glass melt from the first melting vessel flows upward through the first vertical chamber, through the cross passage and then downward through the second vertical chamber to refine and homogenize the glass melt from the first melting vessel. A vacuum preferably is applied to the cross passage to assist upward flow of the glass melt through the first vertical chamber.
The cross passage preferably receives cullet to mix with the glass melt prior to and during flow through the second vertical chamber. The cross passage can have an input for receiving additional materials such as silica and minor ingredients or additives so that such additional materials are mixed with the glass melt during flow through the cross passage and the second vertical chamber. As an alternative, a second melting vessel can be operatively disposed between the first melting vessel and the first vertical chamber for adding additional materials such as silica and minor additives to the glass melt prior to passage through the first vertical chamber. In such modification, vacuum can be applied to the first and/or second melting vessel at least partially to refine the glass melt prior to passage through the first vertical chamber.